The biological evaluation of fusidic acid and its hydrogenation derivative as antimicrobial and anti-inflammatory agents

Background

Fusidic acid (FA) (WU-FA-00) is the only commercially available antimicrobial from the fusidane family that has a narrow spectrum of activity against Gram-positive bacteria.

Methods

Herein, the hydrogenation derivative (WU-FA-01) of FA was prepared and both compounds were examined against a panel of six bacterial strains. In addition, their anti-inflammatory properties were evaluated using a 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mouse ear edema model.

Results

The results of the antimicrobial assay revealed that both WU-FA-00 and WU-FA-01 displayed a high level of antimicrobial activity against Gram-positive strains. Moreover, killing kinetic studies were performed and the results were in accordance with the minimum inhibitory concentration and minimum bactericidal concentration results. We also demonstrated that the topical application of WU-FA-00 and WU-FA-01 effectively decreased TPA-induced ear edema in a dose-dependent manner. This inhibitory effect was associated with the inhibition of TPA-induced upregulation of proinflammatory cytokines IL-1β, TNF-α, and COX-2. WU-FA-01 significantly suppressed the expression levels of p65, IκB-α, and p-IκB-α in the TPA-induced mouse ear model.

Conclusion

Overall, our results showed that WU-FA-00 and WU-FA-01 not only had effective antimicrobial activities in vitro, especially to the Gram-positive bacteria, but also possessed strong anti-inflammatory effects in vivo. These results provide a scientific basis for developing FA derivatives as antimicrobial and anti-inflammatory agents.

Intraluminal Brachytherapy for Malignant Endobronchial Tumors: An Update on Low-Dose Rate Versus High-Dose Rate Radiation Therapy

Although the evolution from low-dose rate (LDR) to high-dose rate (HDR) brachytherapy for malignant endobronchial tumors was presumably based on economy, patient convenience, and radiation protection, our experience with both modalities permits assessment of the pros and cons of each technique. In November 1991, our HDR remote afterloading brachytherapy unit became operational. By that time, we had treated 110 patients (group 1) with malignant endobronchial obstruction with LDR brachytherapy. Since then, all patients have been treated with HDR brachytherapy. The outcome of our first 110 patients (group 2) treated with HDR brachytherapy is presented in this communication, using group 1 as the historic control group. In group 1, patients were treated with 1 or 2 sessions of 30-60 Gy, each calculated at a 1-cm radius. In group 2, patients received 3 or 4 weekly treatments of 7 Gy, each calculated at a 1-cm radius. The majority of patients in each group had previously received a full course of external beam irradiation, and a history of laser bronchoscopy was also similar for the 2 groups. Differences in bronchoscopic response rate (82% vs. 96%, respectively) and complications (3.6% vs. 2.7%, respectively) were statistically insignificant between the LDR group and the HDR group. We believe HDR brachytherapy is the state-of-the-art modality in intraluminal therapy for endobronchial malignancies.

Stat1 as a component of tumor necrosis factor alpha receptor 1-TRADD signaling complex to inhibit NF-kappaB activation

Activated tumor necrosis factor alpha (TNF-alpha) receptor 1 (TNFR1) recruits TNFR1-associated death domain protein (TRADD), which in turn triggers two opposite signaling pathways leading to caspase activation for apoptosis induction and NF-kappaB activation for antiapoptosis gene upregulation. Here we show that Stat1 is involved in the TNFR1-TRADD signaling complex, as determined by employing a novel antibody array screening method. In HeLa cells, Stat1 was associated with TNFR1 and this association was increased with TNF-alpha treatment. TNFR1 signaling factors TRADD and Fas-associated death domain protein (FADD) were also found to interact with Stat1 in a TNF-alpha-dependent process. Our in vitro recombinant protein-protein interaction studies demonstrated that Stat1 could directly interact with TNFR1 and TRADD but not with FADD. Interaction between Stat1 and receptor-interacting protein (RIP) or TNFR-associated factor 2 (TRAF2) was not detected. Examination of Stat1-deficient cells showed an apparent increase in TNF-alpha-induced TRADD-RIP and TRADD-TRAF2 complex formation, while interaction between TRADD and FADD was unaffected. As a consequence, TNF-alpha-mediated I-kappaB degradation and NF-kappaB activation were markedly enhanced in Stat1-deficient cells, whereas overexpression of Stat1 in 293T cells blocked NF-kappaB activation by TNF-alpha. Thus, Stat1 acts as a TNFR1-signaling molecule to suppress NF-kappaB activation.

Low dose rate versus high dose rate intraluminal brachytherapy for malignant endobronchial tumors

Although the evolution from low dose rate to high dose rate brachytherapy for malignant endobronchial malignancies was primarily based on economy, patient convenience, and radiation protection, the difference in therapeutic index, if any, between these two modalities must be kept in mind. Our experience with both methods permits assessment of the feasibility of replacing low dose rate brachytherapy with high dose rate brachytherapy. Results with our first 110 patients (group 1) treated with low dose rate brachytherapy (133 procedures) were compared with results with our initial 59 consecutive patients (group 2) treated with high dose rate brachytherapy (161 procedures). In group 1, patients were treated with one or two sessions of 30-60 Gy each calculated at a 1 cm radius. In patients in group 2, we aimed at three weekly sessions of 7 Gy each calculated at a 1 cm radius. External beam irradiation therapy had previously been given to 88% of patients in group 1 and to 85% of patients in group 2. Laser bronchoscopy was performed in 36% of patients in group 1 and in 24% of patients in group 2 before brachytherapy. Clinical or bronchoscopic improvement was noted in 72% of patients in group 1 and in 85% of patients in group 2 (p > 0.05). Complication rates were low and comparable. Survival was similar in both groups (median < 6 months). Although both low dose rate and high dose rate brachytherapy appear equally effective in palliation for malignant endobronchial obstruction, we are now practicing the latter exclusively.

Secondary hypertension due to renin secreting tumor: a case report

We report a 20-year-old female with severe hypertension, hypokalemia, hyperaldosteronism and elevated level of plasma renin activity (PRA). The clinical diagnosis of renin secreting tumor of left kidney was made before surgery by the lateralization of plasma renin activity via selective renal venous blood sampling and CT scan of kidney. Prompt normalization of blood pressure and decrease of PRA and aldosterone levels were found after surgical removal of the tumor. The pathological findings showed a juxtaglomerular cell tumor.

Major coronary sinus abnormalities: identification of occurrence and significance in radiofrequency ablation of supraventricular tachycardia

Coronary sinus catheterization is important in electrophysiologic study of patients with supraventricular tachycardia. It can provide an anatomic guide for localization of slow atrioventricular nodal pathway and accessory pathways in the posteroseptal area and left-sided atrioventricular ring. However, the morphologic features of the coronary sinus and its significance in patients with supraventricular tachycardia have not been determined. Four hundred eight patients with accessory pathway-mediated tachyarrhythmia and atrioventricular nodal reentrant tachycardia underwent coronary arteriography for a coronary sinus venogram before electrophysiologic study and radiofrequency ablation. The venous phase of left coronary arteriography that delineated the morphologic features of the coronary sinus was carefully evaluated and recorded in multiple projections. Major coronary sinus abnormalities were defined, and they were found in 12 patients (2.9%). Six patients had angulation of the coronary sinus, 4 patients had hypoplasia of the coronary sinus, 1 patient had narrowing of the proximal coronary sinus, and 1 patient had a fistula from persistent left superior vena cava to the coronary sinus. Of 175 patients with atrioventricular nodal reentrant tachycardia, only 1 patient had major coronary sinus abnormalities (proximal angulation), whereas of 233 patients with accessory pathway-mediated tachycardia, 11 patients had major coronary sinus abnormalities (0.6% vs 4.7%, p < 0.05). The accessory pathways in patients with major coronary sinus abnormalities were located exclusively in the left free wall and posteroseptal area. Proper coronary sinus catheterization could be accomplished in 396 patients with a normal coronary sinus, whereas it could be accomplished in only 1 of the 12 patients with major coronary sinus abnormalities (396/396 vs 1/12, p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)